I've had all of AsRock's Extreme/Deluxe AMD boards across my bed already.

Sadly, no reviews (or pictures) can be taken, as they were ES boards. Not meant to be released to the public. Though only minor changes were made to them. They dropped the USB 3.0 internal headers from two of the boards, and changed the 870's PCIe arrangement.

I've done work with companies in this regard because my name has merrit. Either from overclocking exploits, or from my work as a reviewer, or from these forums.

Some companies watch the community, and often enough, when they want to release something to target a certain aspect of the market, they consult someone.

I've done consulting with Cooler Master, Ducky, AsRock, and others. It's almost always 0 Gain work though.
On the flipside, I get access to some products or designs (IE: mechanical drawing of a case, or pictures of a prototype) before others (even some folks in those companies) do, so I can submit my opinion and any design changes I might have in mind.